1. Field of the Invention
The invention relates to an image sensor, and more particularly to an image sensor capable of signal-range adjustment.
2. Description of the Related Art
A semiconductor image sensor (e.g. a charge-coupled device (CCD) or a complementary metal oxide semiconductor (CMOS) sensor), commonly implemented in a camera or a camcorder, is used to convert visible light images into electronic signals, so as to perform subsequent storage, transmission or display.
In some applications, a pixel array of the image sensor has background light. Thus, in addition to the actual sensed signals, the output signals sensed by the image sensor further comprise a background signal caused by the background light. The background signal has a significant signal energy, thus a high-resolution (high bit number) analog-to-digital converter is needed to convert the images traditionally, so as to effectively identify the actual sensing signals.